December 31, 2008
Genetic Testing: People Not Ready for Unclear Results
National Public Radio's All Things Considered had a short story on a family who decided to have some genetic testing completed after a loved one died of cancer. The results were not quite what they expected. Here is an excerpt from the show,
"Information is power," has become a common mantra. But for many people seeking answers through genetic testing, all the DNA probing ends in this twist: Less certainty, not more. This sometimes leads to tough personal decisions amid ambiguity. Nashville novelist Susan Gregg Gilmore learned this lesson the hard way.
Gilmore, a happily married, 47-year-old mother of three daughters, sought testing for flaws in two long genes known as BRCA 1 and BRCA 2. A number of mutations in those genes, first identified in the mid-1990s, have been strongly associated with an increased risk of breast and ovarian cancers.
The risk is particularly elevated for women; having one of the harmful mutations increases the lifetime risk of breast cancer to somewhere between 36 percent and 85 percent, according to the National Cancer Institute. The range reflects the differing risk estimates that have turned up in different studies. A BRCA mutation increases the ovarian cancer risk to between 16 percent and 60 percent.
Though she had heard of the test, Gilmore says, she never thought much about it before getting a call from her mother-in-law, Martha, a few years ago. Eighteen months after defeating breast cancer, Martha Gilmore, a Methodist minister, was diagnosed with ovarian cancer, at age 63. Though most cases of breast and ovarian cancer are not inherited, Martha and her doctors wondered if a BRCA mutation might be behind both diseases in her case. She had called to tell Susan that she was considering taking the test so that her children and grandchildren would have more information. . . .
Martha did turn out to have one of the mutations in BRCA 1 that's been tied to cancer. Eventually, she died of the illness, with Susan and other family members at her bedside. And not long after Martha's funeral, further testing showed that her son Dan Gilmore — Susan's husband — had also inherited the mutation. . . .
. . . she decided, would be to get tested herself for BRCA mutations. It would put her mind at rest, and give her daughters "a more complete medical history on both sides of our family." Susan's mother is still alive and healthy, and Susan has lots of middle-aged female cousins and sisters who are all cancer-free. The doctors told her it was extremely unlikely she had a BRCA mutation. All the more reason to get tested, she thought. . . .
Susan and her family had been counting on good news — or at least a clear thumbs up or thumbs down. But, as the counselor explained, a variant mutation of "undetermined significance" turns up in roughly 10 percent of all case of BRCA tests, and even more often among African-American families. It means there is definitely a mutation, but one that hasn't been linked to illness, in all the research that's been done so far. Susan's "variant" could turn out to be harmless … or not. At this point, no one can say for sure. . . .
"I thought, 'Can we not catch a break here in this genetics game? And what is this variant? And quit telling me that it's of undetermined significance, because I can tell you right now, it is feeling extremely significant," she says. What she really wanted to know, she says, was whether she should she have her ovaries removed, "just in case." She consulted several doctors and genetic counselors, but, much to Susan's frustration, they all stopped short of direct advice.
"I totally relate to the frustration," says Beth Peshkin, a genetic counselor the family consulted at the Lombardi Comprehensive Cancer Center at Georgetown University in Washington, D.C. "Because I think, as clinicians, we would like to have more definitive answers as well."
As Peshkin explained to Susan, the BRCA test has proved to be quite helpful over the years, particularly to families who have a widespread family history of ovarian and breast cancer across several generations. Once the particular mutation has been identified that's behind a family's cancer, any member who tests negative for that mutation can be considered truly negative. That's the good news result. The risk of that person getting cancer is no higher than the risk among the general population, and those who get that news can be certain they won't pass the family cancer gene on to their children. . . . But the catch is this: Increasingly, with more healthy people from healthy families seeking testing than ever before, the results coming back are often much harder to interpret. "Today," Peshkin says, "maybe half the people seeking BRCA testing get back results that are uninformative for one reason or another."
December 31, 2008 | Permalink
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